Power ratchet wrenches which are held in the hand and are driven by a motor are commercially known in the art. Such ratchet wrenches typically embody a handle part and a head portion, wherein the head portion has a pair of ears extending therefrom which house a reciprocating yoke and a ratchet mechanism housed within the yoke. A drive motor is positioned in the handle to drive the reciprocating yoke. Typically these drive motors have been pneumatic, however other motors have also been utilized as well. In pneumatic power ratchet wrench types, the end of handle portion contains a compressed air inlet port which connects to a compressed air supply by various means known in the art. An actuation button or lever is located between air inlet port and housing, which allows the operator to actuate the pneumatic motor, the drive mechanism and ratchet mechanism.
Prior art power ratchet wrenches all require a tensioning means to hold the ratchet mechanism in position while the yoke is reciprocating back to an initial drive position, otherwise, the ratchet mechanism would reciprocate with the yoke. This frictional force is typically referred to as head tension or simply tension. Tension is typically provided by a spring such as a wave spring or Bellville washer which biases the ratchet mechanism against one of the ears of the head or a bushing attached to the ears of the head. Other prior art devices utilize springs which bias a ball against one of the ears of the head or a bushing attached to the ears of the head. A problem with these prior art power ratchets is that this frictional force must be overcome when the yoke is driving the ratchet mechanism, thus reducing the efficiency of the ratchet. Another problem with these prior art power ratchets is that when torque is applied to the ratchet head, the ears of the ratchet head begin to widen apart or spread. Upon repeated application of torque to ratchet head, the ears may remain in a spread position. This causes ratchet mechanism to function improperly because the ears no longer hold the tensioning means in a compressed state and the resulting loss of tension allows the ratchet mechanism to reciprocate with the yoke.
This is a significant problem in prior art ratchet head designs and increases the costs to maintain these ratchet wrenches for both the end user/owner and the ratchet wrench manufacturers. Therefore, there is a need for an improved ratchet head design which maintains proper operation of the ratchet mechanism of the power ratchet wrench by overcoming at least one of the problems identified in the prior art power ratchet wrenches.